Sheet metal fasteners



March 17, 1964 J. ROSAN 3,125,146

SHEET METAL FASTENERS, DRIVING TOOLS, AND METHOD OF DRIVING Filed Dec. 16, 1959 3 Sheets-Sheet 1 IN V EN TOR.

A TTORNE Y Jbae vb Rasa'n March 17, 1964 J. RosAN 3,125,146

SHEET METAL FASTENERS, DRIVING TOOLS, AND METHOD OF DRIVING Filed Dec. 16, 1959 3 Sheets-Sheet 2 IN VEN TOR.

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SHEET METAL FASTENERS, DRIVING TOOLS, AND METHOD OF DRIVING March 17, 1964 3 Sheets-Sheet 3 Filed Dec. 16, 1959 lZZ lZI

INVENTOE. Jofle ph Rama BY United States Patent Ofiice 3,125,146 Patented Mar. 17, 1964 Engineering Corporation, Newport Beach, Calif., a corporation of California Filed Dec. 16, 1959, Ser. No. 860,015 8 Claims. (Cl. 151-4153) This invention relates to novel fasteners adapted to be attached to relatively thin sheets of metal or malleable metal castings or the like having apertures into which the fasteners are inserted. The invention further relates to novel drive tool structures for use in securely attaching the fasteners within said apertures, and to a method of driving such fasteners.

This application is a continuation-in-part of application Serial No. 596,708, filed on July 9, 1956, which was abandoned after filing of the instant application.

In the manufacture and fabrication of various structures, particularly those comprising parts composed of relatively thin and/ or easily milleable materials, difficulties are often encountered in supplying such structures with dependable fastening means. One such difficulty arises when one attempts to satisfactorily tap a thread in a hole in a thin plate or the like, even when the hole can be drilled with comparative ease. Another difficulty resides in the relative weakness of fastenings where the threaded hole is formed in relatively thin and/ or easily malleable material. A further difficulty resides in the frequent necessity of providing bosses on relatively thin and/ or easily malleable plates or castings to supply sufiicient material in the bolt fastening threads to meet the expected strain imposed by the bolt.

It is, therefore, the general purpose and object of this invention to provide a simple, practical and efficicnt internally threaded fastener element adapted to be inserted into an aperture in a relatively thin metallic sheet, or readily malleable material, and permanently secured thereto for engagement by a complementary threaded fastener element, such as a screw or stud.

Another object is to provide a novel fastener element having axially spaced flanges forming a recess therebetween into which the portion of the relatively thin sheet or readily malleable material in the region of the aperture in which the fastener element is inserted, is displaced or caused to fiow, by the application of pressure to provide a strong bond between the fastener and the material in which it is mounted.

A further object is to provide a novel fastener element adapted to be attached to a relatively thin sheet or readily malleable material by inserting a portion within an aperture in the material and producing a bond by causing some of the material about the aperture to flow into a recess in the fastener without substantial thinning and/ or weakening of the material surrounding the aperture.

A further object is to provide a novel fastener element adapted to be inserted in an aperture in a relatively thin sheet or readily malleable material and bonded therein, by a flow of some of the material surrounding the aperture into a recess formed in the fastener element, so that said fastener is secured against axial separation and relative rotation.

A further object is to provide a novel fastener of the character described, in which a portion of the fastener element is adapted to be deformed during mounting or setting so that part of the fastener element penetrates the material to cause a flow of some of the material surrounding the aperture into an annular recess in the'fastene'r element to provide a strong bond, and in' which the fastener itself includes structure to limit the amount of such deformation and penetration.

A further object is to provide a novel tool to drive or set fastener elements of the type disclosed in a relatively thin sheet or readily malleable material.

A further object is to provide a novel tool to deform a portion of fastener elements of the type disclosed herein, to set the same in a relatively thin sheet or readily malleable material.

A more specific object is to provide a drive tool for a fastener element of the type disclosed herein, which will limit the extent of penetration of the fastener into the member in which it is being mounted, and further, to provide such tool which will not mar the surface of said member.

A further object is to provide a method of mounting a grooved element in an aperture in a member by applying pressure, and deforming a portion of the fastener to force the material of the member in the region of the aperture to flow into said groove to form a mechanical bond between the fasteners and member.

A still further object is to provide a method as described above in which the application of pressure and deformation are effected simultaneously to produce the mechanical bond.

Other and more specific objects and advantages will appear and be brought out more fully in the following description, reference being made to the accompanying drawings wherein:

FIG. 1 is an enlarged side view, in quarter section, of an incompletely formed fastener element embodying this invention;

FIG. 2 is a similar view of the completely formed fastener element illustrating a portion of a sheet element to which it is to be secured;

FIG. 3 is a lower end view of the fastener element of FIG. 2;

FIG. 4 is a view similar to FIG. 2 showing a portion of a modified sheet element to which the fastener element is to be secured;

FIG. 5 is a view showing the fastener element after it has been set and secured to the sheet element of either FIG. 2 or FIG. 4; 7

FIG. 6 is a side view, in quarter section, of a modified form of fastener element, the lower portion of a drive tool for said fastener element being shown in cross-section;

FIG. 7 is a plan view of the fastener element of FIG. 6;

FIG. 8 is a cross-sectional view of a complete drive tool such as shown in FIG. 6;

FIG. 9 is a view illustrating the fastener element of FIG. 6 driven by the tool of FIG. 8 into a relatively thin sheet metal material, the tool and the sheet material appearing in cross-section, and the fastener element appearing in side view in quarter section;

FIG. 10 is a fragmentary sectional view corresponding to a portion of FIG. 9, but illustrating a modified form of tool having a marginal rim for limiting the maximum penetration of the abutment flange of the fastener element into the sheet material;

FIG. 11 is a view similar to FIG. 10, but illustrating a drive tool provided with means to prevent marring of the sheet material by the tool;

FIG. 12 is a view of the fastener element of FIG. 6 driven into a relatively thin sheet material by another form of tool, the fastener element appearing in side view, quarter section, and the material and tool appearing in full cross-section with the position during an early stage of installation shown at the left of the vertical center line, and a somewhat later position shown to the right of that center line;

FIG. 13 is a cross-sectional view of the fastener element of FIG. 6 shown driven into a relatively thin sheet metal material by still another form of drive tool;

FIG. 14 is a side view, in quarter section, of still another form of fastener element adapted to be deformed, and including a crown to limit deformation and penetration into a mounting member;

FIG. 15 is a lower end view of the fastener element of FIG. 13;

FIG. 16 is a side view, partly in section, showing the upper end of the fastener element of FIG. 14 in position in an aperture in a relatively thin sheet material and engaged by a modified form of driving tool, the material and tool appearing in section; and

FIG. 17 is a view similar to FIG. 16, showing the fastener element, in quarter section, driven into the sheet metal material.

Referring to FIGS. 1 to of the drawings, the numeral 20 indicates generally a fastener element embodying one form of the present invention, this element being made of any suitable malleable material such as steel, iron, aluminum, etc., and having a generally cylindrical or tubular body 22. During fabrication, the body 22 is provided with a bore 24 and later, if desired, internal threads 26. The body is slotted at its upper or outer end, as shown at 28, to provide a plurality of resilient fingers 30. These fingers are given a radially inward permanent deformation, as indicated by the wedge-shaped slots 28 in FIGS. 2, 4, and 5, which has the effect of giving to the threads 26, in the split upper portion of the body 22, a smaller pitch diameter than the threads in the portion that is not so split. This arrangement produces a spreading action when a screw or threaded bolt (not shown) is inserted into the body member, and the resilient fingers will act as a locking means to prevent inadvertent unscrewing of the screw or bolt.

The body 22 is formed with an annular pilot flange 32 at its inner end, and with an annular abutment flange 34 spaced therefrom, thus forming an annular recess or groove 36 therebetween, the base or bottom wall 38 of which is approximately of the same diameter as the body 22. The recess 36 has a lower radial side wall 40, comprising a side face of the pilot flange 32, and an upper radial side wall 42, comprising the lower side face of the abutment flange 34. These walls are parallel, and each lies in a plane normal to the longitudinal axis of the body 22. The periphery of the abutment flange 32 is serrated, either straight or otherwise, to form a plurality of axially directed, saw tooth-like teeth 44, having portions 46 projecting above and other portions 48 projecting below the upper and lower faces of the abutment flange 34. As shown in FIGS. 2 and 4, the lower extensions or projections 48 have upwardly and inwardly inclined surfaces 52 extending from the lower tips of the teeth to the roots thereof. These upwardly and inwardly inclined surfaces 52 extend from a point about midway of the radial extent of the teeth to the root of the serrations, while the outer extremities of the projections have upwardly and outwardly inclined surfaces 50 extending to the crests of the teeth. The terms upwardly and downwardly, as used herein, are intended only as relative, and describe the directions of the inclinations when the fastener is in the upright position shown in the drawings. By upwardly is meant in a direction toward the slotted end, and downwardly refers to a direction away from said slotted end.

FIG. 2 illustrates the fastener in a position above a body of parent material 54, which is shown in the form of a relatively thin sheet metal element to which the fastener is to be secured. The element 54 may be of steel, iron, aluminum or a like material so long as it is considerably softer or more malleable than the material of the fastener element 20. The sheet 54 is provided with an aperture 56 of a size to snugly receive the pilot flange 32. It will be observed that the abutment flange 34 is considerably larger in diameter than both the aperture and the pilot flange, so as to overlie the rim of the aperture a substantial amount. As an example,

the dimensions of a fastener for use in a .500 inch diameter aperture 56 would have a pilot flange 32 of .498 inch diameter, and an abutment flange maximum diameter of .56 inch. The axial thickness of the abutment flange is .094 inch and the axial distance between the lower face of the abutment flange and the lower face of the pilot flange is also .094 inch. From the foregoing, it will be seen that the abutment flange overlap relative to the aperture 56 is in the form of a ring, the external diameter being .06 inch greater than the aperture, and .062 inch greater than the diameter of the pilot flange 32. The axial width of the groove 36 is slightly greater than the axial thickness of the pilot flange 32. The overall height of the element is .38 inch. The outside diameter of the body 20 may be equal to the diameter of the bottom 38 of the groove 36, i.e., 448 inch. Thus, the radial depth of the groove or recess 36 is equal to the diameter (.498 inch) of the pilot flange minus the diameter (.448 inch) of the body, divided by two or Likewise, the diflerence in diameter between the abutment flange 34 and the pilot flange 32 is equal to .056 inch minus .498 inch, or .062 inch. Dividing this amount by two, the radius of the abutment flange is only .006 of an inch in excess of the radius of the pilot flange, plus the radial depth of the recess 36. From the foregoing, it will be seen that the maximum outer diameter of the abutment flange, including the teeth, is greater than that of the pilot flange by at least twice the radial depth of the recess.

FIG. 4 shows an arrangement in which the sheet metal element 54 is provided with an upwardly projecting dimple 58, which has the effect of increasing the diameter of the upper edge of the aperture 56 to facilitate the insertion of the pilot flange 32.

The method of mounting the fastener 20' in the sheet 54 is as follows:

The lower end of the fastener is inserted into the aperture 56, the pilot flange 32 serving as a guide means to facilitate insertion and to assure centering of the fastener in the sheet metal element. Opposed compressive forces are applied to the upper surface of the abutment flange 34 and to the lower surface of the parent or sheet metal elemen-t 54 in the area thereof surrounding the aperture 56. These forces may be applied by a specially designed drive tool acting downwardly on the upper surface of flange 34 against the support provided by a flat anvil on the lower surface, or vice versa. As the material from which the fastener is made, or at least the material of the abutment flange 34 is made, is considerably harder or less malleable than the material of the sheet metal element 54, the application of the opposed compressive forces will cause the flange 34 to penetrate said element and produce an extru sion or a fluid flow of the softer material of the element into the recess 36, as shown at 59 in FIG. 5. This fluid .025 inch v flow of material will completely fill the recess 36 and, be-

cause of the relatively greater diameter of the abutment flange 34, very little penetration of the abutment flange into the sheet metal material 54 will be required to produce suflicient flow to fill the recess 36. At the same time, the projections or extensions 48 of the teeth 44 will be forced into the upper surface of the sheet metal element 54, thereby assisting in producing the above-mentioned flow, and effecting a locking engagement between the fastener 20 and the sheet metal element 54 that will resist relative axial movement and rotation between the fastener and the sheet metal element. The inclined surface 52 on the projections or extensions 48 will assist inforcibly producing a flow of some of the material of the sheet metal element in a direction inwardly toward the recess 36.

Because of the above-described structure, that is, the beveled or inclined faces 52 of the teeth 44, the relative hardness of the material of the fastener 20 and the sheet metal element 54, the projections 48 of the teeth 44 do not undergo any substantial deformation when the fastener is driven by opposed compressive forces into the sheet metal element 54, but retain the form shown in the drawings to cause a displacement of the adjacent material inwardly into the recess as shown at 59 in FIG. 5.

The upper and lower edges of the threaded bore 26 of the fastener 2t) are chamfered at 60 and 62, respectively, to facilitate the insertion of a screw or threaded bolt.

FIGS. 6 to 12 show a slightly modified form of the fastenor of FIGS. 1 to 5, the corresponding parts being designated by the same reference character with the addition of the superscript prime. In this form of the invention, the fastener 26' comprises a body portion 22 having a threaded bore 26', a pilot flange 32', and a spaced abutment flange 34' providing between them a groove or recess 36, having a bottom wall or base 38', a lower side wall 40' and an upper side wall 42. The periphery of the abutment flange 34 is serrated to'form teeth 44'.

In this form of the invention, the walls 40 and 42 are not parallel, but the lower face of the abutment flange 34' is undercut to form the inwardly and upwardly inclined surface 42, which extends from the tips of the teeth 44 to the bottom or base 38' of the recess 36, as is clearly shown in FIG. 6.

The fastener 20"can be set or driven in the same manner as the fastener of FIGS. 1 to 5. The inclined surface 42 will function in the nature of a camming surface to induce the radial inward flow of the material of the sheet metal element 54 to completely fill the groove, as shown at 59' in FIG. 9'. As in the previously described form, the

teeth 44 will engage the upper surface of the sheet metal element and penetrate the material to form a positive lock, thereby preventing rotation between the fastener and the sheet metal element.

In both forms of the invention above-described, the fastener can be driven into the sheet metal by pressure forces parallel with the axis of the fastener without any deformation of the abutment flanges 34 and 34. In the illustration of FIG. 5, the fastener 20 is shown to have been driven without any deformation of the fastener. In this form, the upper surface of the abutment flange, lying in a plane normal to the longitudinal axis of the body 22, is engaged by a driving tool having a parallel driving surface. The abutment flange, therefore, is not deformed, and will lie in the same plane after being driven, as shown in FIG. 5. The pressure forces will tend to flatten the upward projections 46 and cause deeper penetration of the lower projections 48 into the sheet metal, but inward metal flow is primarily facilitated by the inclined tooth portions 52 and the pressure of the unserrated portion of the abutment flange 34 against the sheet.

FIGS. 9, 10, 11, 12, and 13 illustrate a method of driving a fastener of the type shown in FIG. 6 into a sheet metal element 54 in which the abutment flange 34 is intended to undergo some form of permanent deformation.

FIGS. 6, 8, and 9 show one form of a drive tool designed to produce the deformation of the abutment flange shown in FIG. 9. Referring particularly to FIG. 8, the tool is generally identified by the numeral 64 and cornprises an elongated cylindrical element 66 of case hardened steel, having a circularaxial bore 68. The tool has an annular end face 70 surrounding the open end of the bore 68. The diameter of the bore 68 is slightly greater than the'diameter of the body 22' so as to provide working clearance about the head or upper portion of the body, as shown to exaggerated scale in FIG. 9. The annular end face 70 has a beveled surface 72 forming an angle of approximately 7 to a plane normal to the longitudinal axis of the tool, said bevel extending inwardly and up 'wardly, as is most clearly shown in FIG. 8. While 7 represents the optimum value for the bevel angle, other angles from 3 to may be employed. The wall of the bore 68 and the surface 72 of the end face 70 are connected by a 45 chamfered portion 74 to accommodate 6 the fillet 76 at the juncture of the body portion 22' and the abutment flange 34'. The outer edge of the end face 70 is surrounded by a 45 charnfered edge 78.

In this form, the tool is slipped over the upper end of the fastener 20' as shown in FIG. 6, in which position the beveled end 70 will contact only the upper outer edges of the teeth 44. The sheet metal element 54' is placed on an anvil A, FIG. 9, and pressure is applied to the tool, forcing the abutment flange 34' into the more malleable sheet metal element 54. The initial application of the force on the extreme outer edges of the teeth 44' will produce a bending or deformation of the abutment flange 34' about its area of juncture with the body 22', the degree of deformation increasing with the radial distance from the body 22. The area of contact of the end face 70 with the flange 34 also increases with the extent of bending, as is clear from FIG. 9.

The application of force, plus the undercut surface 4-2 of the abutment flange 34', will effect the desired radial inward flow of the material 59 into the groove 36'. The bending of the flange 34' has no effect on the shape of the body 22, and does not interfere with its intended function of receiving a threaded bolt or screw. Furthermore, the forces are applied at a point remote from the body so that the shear forces on the flange adjacent the body are materially reduced.

While mention has been made above to applying force to the abutment flanges 34 and 34' to set the fasteners, such force can be applied by mounting the tool 64 in a press. However, the preferred and simplest way to set the fasteners is to apply one or more hammer blows to the outer end of the tool 64 to set the fasteners by impact pressure.

FIG. 10 is a fragmentary view illustrating a drive tool 64 including all of the essential features of the tool 64 plus the additional feature of an annular rim 8t} surrounding a beveled face 70'. The purpose of the rim $0 is to limit the extent to which the abutment flange 34' will penetrate the sheet 54, and thereby prevent overdriving of a fastener by the tool 64'. The rim 80 has a flat end face 82 and extends a considerable distance beyond the outer periphery of the teeth 44' so that, in a driving operation in which the outer edge of the abutment flange 34- is deformed and caused to penetrate the sheet metal element 54', the engagement of the end face of the rim with the upper surface of the sheet metal element 54', as shown, will positively limit the penetration of the abutment flange 44 into said sheet metal element. It will be noted that penetration is limited so that the portion of the upper surface of the abutment flange 34', adjacent the body 22', is not deformed.

FIG. 11 is a View similar to FIG. 10, but showing a drive tool 64" similar to the tool 64, but modified by forming a rim 80' of less height than the rim 80 and suitably bonding a ring 84 of nylon or other nonmetallic material thereto for the purpose of preventing marring of the surface of the sheet 54' by the tool 64 during a fastener setting operation.

In FIG. 12 there is shown the lower end of another form of driving tool 132, having an axially extending bore 134 to snugly receive the body 22 of the fastener The tool 132 has a counterbore 138 of a diameter substantially large than the diameter of the body 22', but less than the outer diameter of the abutment flange 34'.

This design provides a rim or annulus 142 at the lower lation it is preferred that it lie in a plane normal to the longitudinal axis of the tool.

The application of impact force or axial pressure on the tool 132 will be eflective to cause the outer edge of the abutment flange 34 to be deformed and penetrate the sheet metal element 54', effecting a greater depth of penetration of this portion than the remainder of the flange and facilitating the flow of the metal 59 into the recess 36'. In the showing of FIG. 12, an early stage in the penetration of the abutment flange 34 into the sheet metal 54' is shown in the portion of the figure to the left of the vertical center line. It will be apparent that in this portion of the figure the flat end surface 144 of the driving tool 132 has engaged the serrated flange 34 only enough to produce the initial penetration into the sheet 54. On the right side of the center line it will be seen that the lower surface 144 of the tool annulus has been traversed downwardly further than on the left side of the figure. This has resulted in causing the annulus 142 to drive the serrated abutment flange 34' more deeply into the sheet metal 54', and also to increase the depth of penetration of the annular rim 142 into the upper surface of the serrated flange 34. This form of the invention has the advantage of avoiding excessive shearing forces at the point where the abutment flange joins the body, which point constitutes the thinnest and consequently the weakest portion of the abutment flange, as will readily be seen from FIG. 6.

FIG. 13 shows another form of driving tool that can be used with a fastener of the type shown in FIG. 6. This tool, designated in its entirety by the numeral 85, includes a body portion having a flat, annular pressure face 87. The body portion has a bore 88 adapted to receive a guide member 89 insertable in the threaded interior of the fastener 20 to align the fastener relative to the tool. The face 87 is surrounded by an upstanding ridge 87a having a transverse cross-section in the form of a right angled triangle, with the vertical wall 87b facing the center of the tool and providing a circular recess 8% having a size to receive the pilot flange 32' for further centering the tool 85 relative to the fastener 20 during setting. The vertical wall 87b is shorter than the axial depth of the pilot flange 30 and the inclined wall 87d is disposed at an angle of about 30 to the horizontal.

In using this form of tool, the pilot flange 32 is inserted in an aperture in the sheet metal element 54', as before described, and the tool 85 is brought into position by the guide rod 80, which aligns the tool relative to the fastener 20'. An annular anvil 85a is applied against the upper surface of the abutment flange 34, and opposing forces are applied to the tool 85 and anvil a, which causes the ridge 87a to force upwardly the metal of the sheet metal element 54' surrounding the aperture. At the same time, the lower surface of the abutment flange 34' is forced to penetrate the upper surface of the sheet metal element 54'. This results in an extrusion or radial inflow of metal into the recess 36' as shown at 90, completely filling the recess and providing a strong bond between the fastener and the sheet metal element. Here again, the teeth 44' will broach into the sheet 54' and lock the fastener 20 against turning.

FIGS. l4, l5, l6, and 17 illustrate a fastener 92 embodying features that serve to limit and indicate when the fastener has been fully set. The fastener is designated as 92 and comprises a body 94 having external threads 96 at the lower end thereof, and internal threads 98 extending through the major length of the body. The fastener includes a pilot flange 100, having an outer diameter which is slightly greater than the crest diameter of the threads 96, and an abutment flange 102, having a serrated portion 104 forming teeth 106. The crest diameter of the serrated portion 104 is considerably greater than the diameter of the pilot flange 100. The abutment flange also includes a crown portion 108, having a diameter considerably larger than the diameter of the serrated portion 104. The upper edge of the crown portion 108 is provided with a 45 bevel desig- 8 nated by the numeral 110, which is adapted to be engaged by a tool, as will be described hereinafter.

The pilot flange and abutment flange 102 are spaced to form a groove or recess 112. The lower surface of the abutment flange 102 is undercut to form a beveled surface 114 extending inwardly and upwardly from the tips of the teeth, the surface 114 forming an angle of approximately 7 with a plane normal to the axis of the fastener. In this construction, the edges of the teeth 106 project downwardly in the form of a point, which is adapted to broach into and be embedded in the upper surface of the sheet metal element in which the fastener is attached to prevent relative rotation as in the preceding modifications. The lower surface of the crown portion 108 is also undercut as shown at 116.

In practice, the threaded end of the fastener 92 is passed through an aperture 117 in a sheet metal element 118, and the pilot flange 100 fits closely within the aperture, as shown in FIG. 16, to retain the fastener in proper position for driving.

The driving operation is performed by a driving tool 120, the working end of which is shown in FIGS. 16 and 17. The driving tool includes a body portion 122 having a bore 124 adapted to receive a guiding rod 125, which is inserted into the threaded interior 98 of the fastener to properly align the tool over the fastener, as shown in FIG. 16, The end of the body portion 122 is conically counterbored at 126 and has a side wall 128 which is beveled on an angle of about 45. During a driving operation, the rod is extended into the fastener, as in FIG. 17, and beveled wall 128 engages the beveled wall 110 of the crown portion 108. Axial pressure is then applied to the tool 120, by impact or otherwise, the lower surface of the sheet metal element resting on an anvil (not shown). In this form of the invention, the axial forces are applied principally to the outer edges of the crown portion, resulting in the penetration of the abutment flange 102 into the material of the sheet metal element 118 surrounding the aperture 117. The outer edge of the abutment flange 102, due to the force being concentrated at a point remote from the center of the fastener, will be downward by and inwardly deformed, as shown in FIG. 17, producing a greater deformation of the crown portion than the serrated portion. This penetration will produce an inward flow of the displaced material of the sheet metal element 118, forcing the metal to completely fill the recess 112, as shown at 130 in FIG. 17. The contacting of the lower edge of the crown portion 108 with the upper surface of the sheet metal 118 (FIG. 16) will limit the inward penetration of the serrated portion 104 and indicate that the fastener has been fully set.

From the foregoing, it is evident that there has been disclosed several forms of sheet metal fasteners, and several forms of driving tools. All of these tools will drive the fasteners into the receiving elements and form a bond between the fasteners and receiving elements by displacement or extrusion, causing forced flow of relatively cold material into the groove or recess between the pilot flange and an abutment flange and providing a continuous body of material filling the recess. At the same time, the lower edges of the teeth on the abutment flange penetrate the receiving element, assisting in inducing the radial inward flow of the metal toward the recess. In all instances the serrations are embedded in the material to interlock therewith, thereby preventing relative rotation between the fastener and the receiving element.

In all forms of the invention, the abutment flange extends radially substantially beyond the pilot flange and overlies a substantial portion of the material of the sheet metal element surrounding the aperture in which the fastener is secured, so that suflicient metal of the sheet metal element surrounding the aperture can be subjected to compression and displaced into and com- 'at points remote from the body member, whereby the danger of shearing the abutment flange is averted while the abutment flange is deformed in amanner to facilitate the flow of the material toward and into the recess Without unduly weakening the sheet metal element in thezone of the fastener.

It will be understood that various changes may be made in the details ofdesign'ofthefasteners and drive tools'disclosed herein without departing from the principles of the invention or the scope of the annexed claims.

'I claim:

1. A metallic fastener forattachment to a workpiece having an aperture therein, said fastener including, a'body of material which is harder than the material of the workpiece and having a pilot flange of approximately the same diameter as thediameter of the aperture in the workpiece in which it is to be mounted, said body having an abutment flange, saidflanges being spaced-apart by an axial wall on said-body to define an annular recess having upper and lower wall portions constituted, respectively, by a portion of the underside of said abutment flange and the upper side of said pilot flange and extending generally normal to the axis of said body, said abutment flange being provided with teeth extending around the outer periphery thereof adapted to be embedded in the metal of said workpiece to positively lock said abutment flange and said bodyagainst rotation relative'to said workpiece, said teeth'being defined by surfaces which merge to form generally axially extending edges, said abutment flange having a diameter, exclusive of said teeth,that is substantially greater than the diameter of saidpilot flange to cause said abutment flange to overlie a substantial portion of the surface of said workpiece surrounding said aperturefthe ends of said teeth including axial portions that extend therefrom slightly beyond the underside of said abutment flange,'said ends having upwardly and inwardly inclined extremities adapted to be embedded in said workpiece toprevent relative rotation between said body and said workpiece and to assist in producing an inward radial flow of metal into said recess,

whereby, upon applying an axial force to said abutment flange in a direction towardsaid workpiece, said abutment flange will be forced into said workpiece, thereby causing a portion of the metal of said workpiece surrounding said aperture to flow radiallyinto and substantially fill said recess, the axial dimension of said recess being substantially less thanlthe thickness of said workpiece so that only asmall penetration of said'large abutment flange into said workpiece is necessary-to displace suflicient metal tofill said recess, said body having-an axially extending extremity portion formed integrally therewith and incorporating a thread 'engageable by-an associated fastener.

2 A metallic fastener for attachment to a workpiece having an aperture therein, said fastener including'a body of materialwhich is harder than the material of the workpiece and having a pilot flange of approximately the same diameter as the diameter of the aperture in the workpiece in which it is to be mounted,-sai'd body having'a'n abutment flange, said flanges being spacedapart by an axial wall on said body to define an annular recess having upper and lower wall portions constituted, respectively, by a portion of the underside of said abutment flange and the upper side of said pilot flange, and extending generally normal to the axis of said body, said abutment flange being provided with teeth extending around the outer periphery thereof adapted to be embedded in the metal 1% 'of said workpiece to positively lock said abutment flange and said body against rotation relative to said workpiece, said teeth being defined by surfaces which merge to form generally axially extending edges, said abutment flange having a diameter, exclusive of said teeth, that is substantially greater than thediameter of each pilot flange, said abutment flange also having a maximum diameter, including said teeth, that is greater than the diameter of said pilot flange by an amount equal to at least twice the radial depth of said recess to cause said abutment flange to overlie a substantial portion of the surface of said workpiece surrounding said aperture, said teeth having extremities adapted to be embedded in said workpiece to prevent relative rotation between said body and said 'piece is necessary to displace suflicient metal to fill said recess, said body having an axially extending extremity portion formed integrally therewith and provided with means for associating the same with a cooperating element.

3. A fastener as defined in claim 2, wherein the means for associating the axially extending extremity portion with a cooperating element comprises a screw thread.

4. A metallic fastener for attachment to a workpiece havingan aperture therein, said fastener including, a body of material which is harder than the material of the workpiece and having a pilot flange of approximately the same diameter as the diameter of the aperture in the workpiece in which it is to be mounted, said body having an abutment flange, said flanges being spaced apart by an axial wallon said body to define an annular recess having upper and lower wall portions constituted, respectively, by a portion of the underside of said abutment flange and the upper side of said pilot flange, at least'the portion of the underside of said abutment flange defining said recess extending generally normal to the axis of said body, said abutment flange being provided with teeth extending around the outer periphery thereof adapted to be embedded in the metal of said workpiece to positively lock 'said abutment flange andsaid body against rotation relative to said workpiece, said teeth being defined by surfaces which merge to form generally axially extending edges, said abutment flange having a diameter, exclusive of said teeth, that is substantially greater than the diameter'of sai-dpilot flange to cause said abutment flange to overlie a substantial portion of the surface of said work piece surrounding said aperture, the ends of said'teeth including axial portions that extend therefrom slightly be- .yond the underside of said abutment flange, saidends having upwardly and inwardly inclined extremities adapted to be embedded in said workpiece to prevent relative rotation between said body and said workpiece andtoassist in producing-an inward radial flow of metal into said recess, whereby, upon applying an axial force to said abutment flange in a direction toward said work! piece, said abutment flange will be forced into said work- .piece, thereby causing a portion of the metal of said workpiece surrounding said aperture to flow radially into and substantially fill-said recess, the axial dimension of said recess being substantially less than the thickness of said workpiece so that only a small penetration of said 5. A fastener as defined in claim 4, wherein the upwardly and inwardly inclined extremity portion of the teeth is disposed upon an angle of about 7 to a plane normal to the axis of the fastener.

6. A fastener as defined in claim 4, wherein the portion of the underside of the abutment flange immediately adjacent to the teeth, is inclined upwardly and inwardly on the same angle as the upwardly and inwardly inclined extremity portion of the teeth.

7. A metallic fastener for attachment to a workpiece having an aperture therein, said fastener including, a body of material which is harder than the metal of said workpiece, said body having a cylindrical pilot flange of approximately the diameter of the aperture in which it is to be mounted, said body having a substantially cylindrical abutment flange, said abutment flange including a cylindrical projection on the underside thereof provided with axially extending saw tooth-like teeth on the outer periphery thereof located inwardly of the outer periphery of said abutment flange, said flanges being spaced apart by an axial wall on said body disposed between said flanges to define an annular recess whose side wall is constituted by said axial wall and whose top and bottom walls are constituted, respectively, by a portion of the underside of said downwardly projecting portion of said abutment flange and the upper side of said pilot flange and extending generally normal to the axis of said body, said teeth being adapted to be embedded in the surface of said workpiece adjacent said aperture to lock said abutment flange against rotation relative to said workpiece, said downwardly projecting portion of said abutment flange having a diameter, exclusive of said teeth, that is substantially greater than the diameter of said pilot flange, said abutment flange also having a diameter, inclusive of said teeth, that is greater than the diameter of said pilot flange by an amount equal to at least twice the radial depth of said recess to permit said projecting portion of said abutment flange to overlie a substantial area of the surface of said workpiece surrounding said aperture outwardly of said pilot flange, said teeth being adapted by embedment in said workpiece to assist in producing an inward radial flow of metal into said recess, whereby, upon the application of an axial force to said abutment flange in a direction toward said workpiece, said projecting portion of said abutment flange will be forced into said workpiece with said underside of said projecting portion causing a portion of the metal of said workpiece surrounding said aperture to flow radially into and substantially fill said recess, the axial dimension of said recess parallel to the longitudinal axis of said body being substantially less than the thickness of said workpiece so that only a small penetration of said projecting portion and teeth into the surface of said workpiece is necessary to displace sufficient metal to fill said recess, the displaced metal in said recess cooperating with ,the upper side of said pilot flange to provide an annular abutment resisting pushout of the fastener equal to the shear strength of the full axial dimension of said displaced metal, said body having an axially extending extremity portion formed integrally therewith and provided with means for associating the same with a cooperating element.

8. A metallic fastener for attachment to a workpiece formed from malleable metal, said workpiece having an aperture therein, said fastener including, a body of material which is harder than the metal of said workpiece, said body having a cylindrical pilot flange of approximately the diameter of the aperture in which it is to be mounted, said body having a substantially cylindrical abutment flange, said abutment flange including a substantially cylindrical projection on its underside provided with axial teeth on the periphery thereof located inwardly of the 12 outer periphery of said abutment flange, said flange being axially spaced apart by an axial wall on said body disposed between said flanges to define an annular recess whose side wall is constituted by said axial wall and whose top and bottom Walls are constituted, respectively, by a portion of the underside of said projection and the upper side of said pilot flange, at least the portion of the underside of said abutment flange defining said recess extending generally normal to theaxis of said body, said teeth being adapted to be embedded in the surface of said workpiece adjacent said aperture to lock said abutment flange against rotation relative to said workpiece, the diameter of said projection on said abutment flange, exclusive of said teeth, being substantially greater than the diameter of said pilot flange to permit said projecting portion of said abutment flange to overlie a substantial area of the surface of said workpiece surrounding said aperture outwardly of said pilot flange, and the ends of said teeth including axial portions which extend downwardly from said projection and which have upwardly and inwardly inclined extremities adapted to be embedded in the surface of said workpiece to prevent relative rotation, said teeth being adapted by embedment in said workpiece to assist in producing an inward radial flow of metal into said recess, whereby, upon the application of an axial force to said abutment flange in a direction toward said workpiece, said projection on said abutment flange will be forced into said workpiece with said underside of said projection causing a portion of the metal of said workpiece surrounding said aperture to flow radially into and substantially fill said recess, the axial dimension of said recess parallel to the longitudinal axis of said body being substantially less than the thickness of said workpiece so that only a small penetration of said projection and teeth into the surface of said workpiece is necessary to displace sufiicient metal to fill said recess, the displaced metal in said recess cooperating with the upper side of said pilot flange to provide an annular abutment resisting push-out of the fastener equal to the shear strength of the full axial dimension of said displaced metal, said body having an axially extending extremity portion formed integrally therewith and provided with means for associating the same with a cooperating element.

References Cited in the file of this patent UNITED STATES PATENTS 625,491 Converse May 23, 1899 1,706,118 Hopkins Mar. 19, 1929 1,827,884 Ellison Oct. 20, 1931 1,855,447 Hagstedt Apr. 26, 1932 1,946,064 Creveling Feb. 6, 1934 1,956,634 Watson May 1, 1934 2,025,223 Watson Dec. 24, 1935 2,025,224 Dodge Dec. 24, 1935 2,127,969 Dingwerth Aug. 23, 1938 2,187,661 Lochrane Jan. 16, 1940 2,325,989 Tryon Aug. 3, 1943 2,358,728 Miller Sept. 19, 1944 2,492,536 Rosan Dec. 27, 1949 2,685,320 Rosan Aug. 3, 1954 2,741,289 Grow Apr. 10, 1956 FOREIGN PATENTS 529,320 Belgium Dec. 3, 1954 500,583 Canada Mar. 16, 1954 944,243 France Nov. 2, 1948 1,178,030 France Dec. 8, 1958 370,948 Great Britain Apr. 8, 1932 757,560 Great Britain Sept. 19, 1956 615,250 Germany July 1, 1935 UNITED STATES PA ENT 'OFFICE CERTIFICATE oFCRREcTIoN Patent No. 3,125,146 l 4 March 17 1964 iJoseph Rosan I It is hereby certified that error appears inithe above numbered pat ent requiring correction and that the; said Letters Patentshould read as corrected below.

Column 1, line 22, for "milleablev read malleable column 2 line 19, for'"fasteners" read fastener colum: 4, line 15, for "20" read 22 r linel for "448" read .448 line 243 for ".056" read 0,56 column 6, 111 62, for "large" read larger-; column 7, line 39, for "30" read 32 column 8, line 42, for "downward by" read downwardly column 9, line 7 for "produce" read prodk column 10, line 6; for "each" read said column ll line 56, for "pushout" read ,pushout r{ column l2 line 1, for "flange" second occurrence, read flanges (SEAL) Signed and sealed this 20th day of April 1965.

Attest:

ERNEST W. SWIDER I' I VEDWARD J. BRENNER Attesting Officer a V v Commissioner of Patents 

1. A METALLIC FASTENER FOR ATTACHMENT TO A WORKPIECE HAVING AN APERTURE THEREIN, SAID FASTENER INCLUDING, A BODY OF MATERIAL WHICH IS HARDER THAN THE MATERIAL OF THE WORKPIECE AND HAVING A PILOT FLANGE OF APPROXIMATELY THE SAME DIAMETER AS THE DIAMETER OF THE APERTURE IN THE WORKPIECE IN WHICH IT IS TO BE MOUNTED, SAID BODY HAVING AN ABUTMENT FLANGE, SAID FLANGES BEING SPACED APART BY AN AXIAL WALL ON SAID BODY TO DEFINE AN ANNULAR RECESS HAVING UPPER AND LOWER WALL PORTIONS CONSTITUTED, RESPECTIVELY, BY A PORTION OF THE UNDERSIDE OF SAID ABUTMENT FLANGE AND THE UPPER SIDE OF SAID PILOT FLANGE AND EXTENDING GENERALLY NORMAL TO THE AXIS OF SAID BODY, SAID ABUTMENT FLANGE BEING PROVIDED WITH TEETH EXTENDING AROUND THE OUTER PERIPHERY THEREOF ADAPTED TO BE EMBEDDED IN THE METAL OF SAID WORKPIECE TO POSITIVELY LOCK SAID ABUTMENT FLANGE AND SAID BODY AGAINST ROTATION RELATIVE TO SAID WORKPIECE, SAID TEETH BEING DEFINED BY SURFACES WHICH MERGE TO FORM GENERALLY AXIALLY EXTENDING EDGES, SAID ABUTMENT FLANGE HAVING A DIAMETER, EXCLUSIVE OF SAID TEETH, THAT IS SUBSTANTIALLY GREATER THAN THE DIAMETER OF SAID PILOT FLANGE TO CAUSE SAID ABUTMENT FLANGE TO OVERLIE A SUBSTANTIAL PORTION OF THE SURFACE OF SAID WORKPIECE SURROUNDING SAID APERTURE, THE ENDS OF SAID TEETH INCLUDING AXIAL PORTIONS THAT EXTEND THEREFROM SLIGHTLY BEYOND THE 